Mechanism of Hertbeat

The SA node is called the pacemaker of the heart because it ____________.

• allows both atria to contract rapidly in response to a signal from one node.

• relays the regulated impulses throughout the heart

• initiates the heartbeat through cells

• has unique muscle fibers that can function without external stimulation.

In what order are the impulses transmitted?

• SA Node, AV Node, Bundle of His, Purkinje Fibers

• AV Node, SA Node, Bundle of His, Purkinje Fibers

• SA Node, Bundle of His, AV Node, Purkinje Fibers

• AV Node, Bundle of His, Purkinje Fibers, SA Node,

The delay at the AV node supports coordinated blood flow through the heart by _____.

• increasing the power of the impulse to maintain its flow through the Bundle of His

• triggering the ventricles to expand in rhythm with the impulses from the Bundle Branches

• allowing the atria time to push blood into the ventricles right before the ventricles contract

• allowing the atria to contract simultaneously as soon as the SA node sends the impulse

Name the main heart pacemaker.

• Atrioventricular node

• Purkinje fibres

• Bundle of His

• Sinoatrial node

The first 'lub' sound is produced when ________ close.

• tricuspid valve

• tricuspid vale and bicuspid valve

• semilunar valve

• bicuspid valve

Closing of semilunar valves produce the second sound '____________'.

• 'dub'

• 'dap'

• 'tab'

• 'lap'